Scientists say we may be closer than most think to finding life beyond our own planet

Many scientists believe we're not alone in the universe, and NASA researchers say discovering if that's true is within their reach.

NASA held a panel discussion at the space agency's headquarters in Washington on Monday about the possibility that life exists elsewhere in the universe and the technological advances being made in an effort to find it. The scientists on the panel said that we may be closer to finding alien life than many people would have thought.

Such a discovery could change not only our world but our perception of our place in it.

"What we didn't know five years ago is that perhaps 10% to 20% of stars around us have Earth-size planets in the habitable zone," said panelist Matt Mountain, director and Webb telescope scientist at the Space Telescope Science Institute. "It's within our grasp to pull off a discovery that will change the world forever. It is going to take a continuing partnership between NASA, science, technology, the U.S. and international space endeavors, as exemplified by the James Webb Space Telescope, to build the next bridge to humanity's future."

This is an artist's concept of the James Webb Space Telescope, which is expected to be launched in 2018 and used to continue the search for planets outside our solar system (Image: NASA).

NASA has been searching the heavens for signs of extra-terrestrial life, whether intelligent or microbial, for years.

The space agency used ground-based observatories before moving to space-based machines like the Hubble Space Telescope, the Spitzer Space Telescope, and the Kepler Space Telescope.

The telescopes can observe thousands of stars and calculate whether the stars have one or more orbiting planets. They also can tell if those planets are the right distance away from its star to hold liquid water, the key ingredient to life as we know it.

At the time, Douglas Hudgins, NASA's exoplanet exploration program scientist, said they'd discovered that there are an abundance of habitable Earth-sized planets in the universe. "Our goal is to find Earth 2.0 -- an Earth-like planet that could hold life," he said.

NASA is looking to load up its quiver of planet-hunting telescopes over the course of the next 10 to 15 years.

The space agency plans to launch its Transiting Exoplanet Surveying Satellite (TESS) in 2017 and the Webb Space Telescope in 2018. There's a proposal to build and launch what's been dubbed the Wide Field Infrared Survey Telescope - Astrophysics Focused Telescope Assets (WFIRST-AFTA) early in the next decade but it is awaiting approval.

Scientists are eager to follow up Kepler's discoveries with the work expected to be done by the Webb Space Telescope, which the space agency calls the next great observatory.

The new telescope is expected to search for the first galaxies that formed in the early universe and hopefully give scientists information about the Big Bang and the Milky Way. It also should provide more information on the hundreds of newly discovered exoplanets.

"Sometime in the near future, people will be able to point to a star and say, 'that star has a planet like Earth,' " said Sara Seager, professor of planetary science and physics at MIT. "Astronomers think it is very likely that every single star in our Milky Way galaxy has at least one planet."